Metal nu-acyl sarcosinate thickened lubricating oils



United States PZIt -t METAL N-ACYL SARCOSINATE THICKENED LUBRICATIN GOILS Joseph F. Lyons, Wappingers Falls, and Paul R. Thomas, Beacon, N.Y., assignors to The Texas Company, New York, N. Y., a corporation ofDelaware No Drawing. Application March 2, 1956 Serial No. 568,993

6 Claims. (Cl. 25233.6)

This invention relates to lubricating greases containing a novelthickener which also functions as an antioxidant and antirustagent.

The grease compositions of this invention comprise an alkali metal oralkaline earth metal salt of an N-C C acyl sarcosine as a thickeningagent and an oleaginous lubricating base. The greases of this inventioncomprise 10 to 40 weight percent N-acyl sarcosine salt and 60 to 90weight percent oleaginous lubricating base. Conventional greaseadditives, such as stabilizers, E. P. agents, etc., may also be added tothe grease compositions of this invention.

The grease compositions of this invention display good oxidationresistance and antirust properties. As a consequence, these greases findparticular application in the lubrication of marine machinery.

Sarcosine is N-methyl glycine. N-acyl sarcosines have the generalformula RCONCHtCOOH wherein R is an aliphatic hydrocarbon radical. TheN-acyl sarcosines whose salts are used as thickening agents contain 10to 24 carbon atoms in the R component of the foregoing formula. Examplesof N-acyl sarcosines used as thickening agent precursors are illustratedby the following: N-lauroyl sarcosine, N-stearoyl sarcosine, N-caproylsarcosine, N-myristoyl sareosine, N-oleoyl sarcosine, N-palmitoylsarcosine, and N-arachidoyl sarcosine.

The N-C C -acyl Sarcosine salts are generally formed in situ during thegrease preparation which is conventional. The N-acyl sarcosine issaponified with alkali metal or alkaline earth metal hydroxide in aportion of the oleaginous lubricating base. The mixture of sarcosinesalt and lubricating oil is dehydrated and subsequently brought to thedesired consistency by the addition of further quantities of lubricatingbase. The details of preparation will be shown in the subsequentexamples.

The N-acyl Sarcosine salts constitute 10 to 40 percent of the greasecomposition. The N-acyl Sarcosine salts are not as effective thickeningagents as the fatty acids, as is evident from the 10 to 40 weightpercent concentration range specified. Although the concentrationrequired for the preparat-ion'of the greases varies with the metal,grease grade and the chain length of the acyl substituent, the usualconcentration of N-acyl sarcosine salt falls between and 35 weightpercent.

The oleaginous lubricating base may be a conventional minerallubricating oil, a synthetic lubricating oil prepared by cracking andpolymerizing products of the Fischer-Tropsch process and thelike or asynthetic oleaginous compound possessing lubricating characteristics andhaving an SUS viscosity within the lubricating oil viscosity range; Theoleaginous base is usually a conventional mineral lubricating oilbecause of the cost fac- 2 tor, but a synthetic base material can besubstituted in all or in part therefor.

The mineral lubricating oils can be a distillate or residual oil and canbe derived from a parafin base, naphthene base or a mixedparaifin-naphthene base crude. These mineral lubricating Oils aresubjected to greater or lesser degrees of refining and solvent dewaxing,depending upon the use intended for the grease composition. Broadlyspeaking, the greases of this invention can be formulated with minerallubricating oils having an SUS viscosity at F. between 50 and 1000, butare usually prepared with base oils having an SUS viscosity at 100 F.between 50 and 300.

The synthetic lubricating bases are usually of the ester or ether type.High boiling esters of aliphatic dicarboxylic acids find particularlywide-spread use in greases adapted for extreme temperature lubrication,that is, lubrication at both high and low temperatures. Examples of thesynthetic polyester lubricating bases are: di-2-ethylhexyl sebacate,di-Z-ethylhexyl azelate, di-n-a-myl sebacate, di-Z-ethylhexyl adipate,.and di-n-nonyl azelate. Polyalkylene ethers such as polyethylene glycol,polypropylene glycol, modified by etherification and esterification ofthe terminal hydroxy radicals, are also useful synthetic lubricatingbases.

Additives to impart anti-oxidant and extreme pressure properties may beincorporated in the greases of the invention. Aromatic amine typeinhibitors have been found particularly effective anti-oxidants;aromatic amines such as N,N,N,N-tetramethyl 4,4'-diamino diphenylmethane, diphenyl amine and phenyl alphanaphthyl amine are preferred.Extreme pressure additives which may be incorporated in the greases aresulfurized fats, sulfurized oils, chlorinated organic compounds such aschloro-substituted waxes, chloro-substituted aromatic compounds andchlorinated olefin polymers and sulfochlorinated compounds such assulfo-chlorinated olefin polymers and olefins derived from waxes.

In the following examples there is illustrated the preparation of thenovel grease compositions of this invention.

EXAMPLE 1 Into a grease kettle there were introduced 246 grams ofN-stearoyl sarcosine, 250 grams of a naphthene base oil having an SUS at100 F. of about 312, a pour point or" --20 F., and a flash COC of 355 F.minimum and 250 grams of water. grams of lithium hydroxide in a 10.3%aqueous solution was gradually added to the reaction mixture as thetemperature was raised to about 210 F. After saponification at 210 F.for about 2 hours, .and dehydration at about 310 F. for about 1 hour, anadditional 350 grams of the naphthene base distillate oil was slowlyadded to the reaction mixture as it slowly cooled. A number 1 gradegrease was obtained having the following composition: 29.4 percentlithium N-stearoyl sarcosinate and 70.6 percent naphthene base oil. Theproperties of this grease are shown in Table I.

EXAMPLE 2 300 grams of N-stearoyl sarcosine, 300 grams of the naphthenebase oil employed in Example 1, 38 grams of lime and 300 grams of waterwere charged to a grease kettle. After saponification at a temperatureabout 210 F. for 2 hours and dehydration at a temperature of about 3l0F. for 1 hour, an additional 1200 grams of naphthene base oil was slowlyadded to the reaction mixture as it was cooled. After passage through aPremier colloid mill, a No. 2 grade grease was obtained having thefollowing composition: 17.5 percent calcium N-stearoyl sarcosinate and82.5 percent naphthene base oil. The properties of this grease are shownin Table I.

, 3 EXAMPLE 3 A mixed sodium-calcium N-stearoyl sarcosine grease wasprepared as follows: 282 grams of N-stearoyl sarcosine, 300 grams of thenaphthene base oil employed in Example 1, 300 grams of Water, 55.5 gramsof sodium hydroxide in a 49.4% aqueous solution and 7.0 grams of limeconstituted the charge to the grease kettle. After saponificaticn at 200F. for about 2 hours and dehydration at 310 F. for about 1 hour, anadditional 1000 grams of naphthene base was added as the mixture wasslowly cooled. The product was a No. 1 grade grease having the followingcomposition: 3.8 percent calcium N-stearoyl sarcosine, 15.0 percentsodium N-stearoyl sarcosinate and 81.2 percent naphthene base distillateoil. The properties of this grease are shown in Table I.

EXAMPLE 4 A lithium N-lauroyl sarcosine grease was prepared as follows:275 grams of N-lauroyl sarcosine, 275 grams of naphthene base oilemployed in Example 1, 275 grams of water and 246 grams of a 10.7aqueous solution of lithium hydroxide constituted the charge to thegrease kettle. After saponification of the grease mixture at 210 F. for2 hours and dehydration at 310 F. for 1 hour, an additional 250 grams ofnaphthene base oil was added as the mixture was slowly cooled down to200 F. The grease was drawn at 120 F. and had the following composition:35% lithium N-lauroyl sarcosinate and 65% naphthene base distillate oil.The properties of this grease are also shown in the accompanying TableI.

4 an alkali metal or an alkaline earth metal N-acyl sarcosine salt as agrease thickening agent.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made with-' out departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

We claim:

1. A grease comprising a major portion of an oleaginous lubricating baseand a metal salt of N-acyl sarcosine of the general formula RC ONCHaCOOH in which R is an aliphatic hydrocarbon radical containing 10 to 24carbon atoms, said metal salt being present in an amount sufiicient toefiect thickening of said lubricating base to grease'consistency andsaid metal being selected from the group consisting of alkali metals,alkaline earth metals and mixtures thereof.

2. A grease comprising a major portion of an oleaginous lubricating baseand the lithium salt of N-stearoyl sarcosine in an amount suflicient tothicken said lubricating base to grease consistency.

3. A grease comprising a major portion of an oleaginous lubricating baseand the calcium salt of N-stearoyl sarcosine in an amount suflicient tothicken said lubricating base to grease consistency.

4. A grease comprising a major portion of an oleaginous lubricating baseand a mixed calcium-sodium salt Table I PROPERTIES OF METAL N-ACYLSARCOSINE GREASES Li Grease of Ca Grease of Na-Ga Grease Li Grease ofExample 1 Example 2 of Example 3 Example 4 Bomb Oxidation, 100 Hr. at210 F.Pres- 1 to 2 p. s. i 5 1:0 6 p. s. i.

sure Drop.

Dropping Point 240 F 280 F. ASTM Penetration at 77 F;

Unworked 277.

Worked 323.

Worked, 100,000 Str 313. Water Washing and Rusting Test:

Grease in bearing, percent 17 6.

Condition of bearing No rust. Dynamic Water Resistance Test, percentloss 100.

Water Absorption, percent 100.

Penetration alter Absorption. Soft grease. Salt Spray, percent Rust 85.Appearance Light tan,

smooth.

The properties of the N-acyl sarccsine metal salt base greases aredependent to a great extent on the metal employed. The lithium l\acylsarcosinate base greases of Examples 1 and 4 exhibit excellent anti-rustand anti-oxidant properties. The excellent anti-oxidant properties areshown in the bomb oxidation test and the anti-rust properties are shownin the water Washing and rusting test. The anti-rust properties of thelithium N-acyl sarcosinate greases are particularly surprising since arust inhibitor is usually required for lithium soap greases in order toobtain a no rust rating in this test. The small change in consistency ofthe lithium N-stearoyl sarcosinate of Example 1 after water absorptionis also surprising. The small loss in the dynamic Water resistance testand the 0% rust in the salt spray test obtained with the calciumN-stearoyl sarcosinate base grease of Example 2 show that the calciumbase greases of this invention have excellent resistance to water andrust.

The properties of the greases shown in Table I illustrate that greasespossessing unusual anti-oxidant, antirust, and water-resistantproperties are obtained using RC ONCH2C O OH in which R is an aliphatichydrocarbon radical containing 10 to 24 carbon atoms and said metalbeing selected from the group consisting of alkali metals, alkalineearth metals and mixtures thereof.

References Cited in the file of this patent UNITED STATES PATENTS2,640,812 Bryant June 2, 1953 2,699,427 Smith et al. Jan. 11, 19552,756,213 Dixon July 24, 1956

1. A GREASE COMPRISING A MAJOR PORTION OF AN OLEAGINOUS LUBRICATING BASEAND A METAL SALT OF N-ACYL-SARCOSINE OF THE GENERAL FORMULA